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[PATCH] Sanitize gdbarch access on probe/SDT API (was: Re: [PATCH] Use "get_current_arch" instead of...)


On Thursday, December 05 2013, Pedro Alves wrote:

> Adding get_current_arch calls outside initial command evaluation
> raises eyebrows.
>
> /* Return "current" architecture.  If the target is running, this is the
>    architecture of the selected frame.  Otherwise, the "current" architecture
>    defaults to the target architecture.
>
>    This function should normally be called solely by the command interpreter
>    routines to determine the architecture to execute a command in.  */
> extern struct gdbarch *get_current_arch (void);

Hm, thanks for the hint, I wasn't aware of such limitation/restriction.

> struct value *
> probe_safe_evaluate_at_pc (struct frame_info *frame, unsigned n)
> {
> ...
>   return evaluate_probe_argument (probe, n);
> }
>
> FRAME here is the context the probe is being evaluated
> in (get_current_frame(), the frame/thread that hit the event,
> passed from infrun.)  It'd be better to use the frame's arch
> explicitly (that is, pass down the frame or arch to
> evaluate_probe_argument).

Right, could you please take a look at the following approach and tell
me what you think?

I tried to use get_selected_frame whenever I could, and when I couldn't,
I used get_current_regcache.

Tom, you asked me to try to use the expression's gdbarch for the
compile_ax method, but as it turns out, the code would be too messy if I
did that, so I have chosen to simplify it and use the agent_expr's
gdbarch instead.

I tested this patch on x86_64 Fedora 17 and ARM Fedora 19, and it works
OK.

Thanks,

-- 
Sergio

2013-12-06  Sergio Durigan Junior  <sergiodj@redhat.com>

	* break-catch-throw.c (fetch_probe_arguments): Use gdbarch from
	selected frame.  Pass gdbarch to sym_get_probe_argument_count and
	sym_evaluate_probe_argument.
	* elfread.c (elf_get_probe_argument_count): Adjust declaration to
	accept gdbarch.  Pass gdbarch to get_probe_argument_count.
	(elf_can_evaluate_probe_arguments): Likewise, but pass gdbarch to
	can_evaluate_probe_arguments.
	(elf_evaluate_probe_argument): Likewise, but pass gdbarch to
	evaluate_probe_argument.
	* probe.c (get_probe_argument_count): Use gdbarch from selected
	frame.  Pass gdbarch to sym_get_probe_argument_count.
	(can_evaluate_probe_arguments): Likewise, but pass gdbarch to
	can_evaluate_probe_arguments.
	(evaluate_probe_argument): Likewise, but pass gdbarch to
	sym_evaluate_probe_argument.
	* probe.h (struct probe_ops) <get_probe_argument_count,
	can_evaluate_probe_arguments, evaluate_probe_argument>: Adjust
	declaration to accept gdbarch.
	* stap-probe.c: Include "regcache.h".
	(stap_parse_probe_arguments): Adjust declaration to accept
	gdbarch.
	(stap_get_probe_argument_count): Likewise.  Pass gdbarch to
	can_evaluate_probe_arguments and stap_parse_probe_arguments.
	(stap_get_arg): Likewise, but pass gdbarch to
	stap_parse_probe_arguments.
	(stap_can_evaluate_probe_arguments): Adjust declaration to accept
	gdbarch.
	(stap_evaluate_probe_argument): Likewise.  Pass gdbarch to
	stap_get_arg.
	(stap_compile_to_ax): Use agent_expr's gdbarch; pass it to
	stap_get_arg.
	(compute_probe_arg): Use gdbarch from selected frame.  Pass
	gdbarch to sym_get_probe_argument_count and
	sym_evaluate_probe_argument.
	(compile_probe_arg): Use gdbarch from agent_expr.  Pass it to
	sym_get_probe_argument_count.
	(handle_stap_probe): Adjust declaration to accept gdbarch.
	(stap_get_probes): Use gdbarch from curret regcache.  Pass it to
	handle_stap_probe.
	(stap_gen_info_probes_table_values): Use gdbarch from selected
	frame.
	* symfile-debug.c (debug_sym_get_probe_argument_count): Adjust
	declaration to accept gdbarch.  Pass it to
	sym_get_probe_argument_count.
	(debug_can_evaluate_probe_arguments): Likewise, but pass gdbarch
	to can_evaluate_probe_arguments.
	(debug_sym_evaluate_probe_argument): Likewise, but pass gdbarch to
	sym_evaluate_probe_argument.
	* symfile.h (struct sym_probe_fns) <sym_get_probe_argument_count,
	can_evaluate_probe_arguments, sym_evaluate_probe_argument>: Adjust
	declaration to accept gdbarch.

diff --git a/gdb/break-catch-throw.c b/gdb/break-catch-throw.c
index fb24725..769559b 100644
--- a/gdb/break-catch-throw.c
+++ b/gdb/break-catch-throw.c
@@ -105,6 +105,7 @@ static void
 fetch_probe_arguments (struct value **arg0, struct value **arg1)
 {
   struct frame_info *frame = get_selected_frame (_("No frame selected"));
+  struct gdbarch *gdbarch = get_frame_arch (frame);
   CORE_ADDR pc = get_frame_pc (frame);
   struct probe *pc_probe;
   const struct sym_probe_fns *pc_probe_fns;
@@ -123,13 +124,13 @@ fetch_probe_arguments (struct value **arg0, struct value **arg1)
   gdb_assert (pc_probe->objfile->sf->sym_probe_fns != NULL);
 
   pc_probe_fns = pc_probe->objfile->sf->sym_probe_fns;
-  n_args = pc_probe_fns->sym_get_probe_argument_count (pc_probe);
+  n_args = pc_probe_fns->sym_get_probe_argument_count (pc_probe, gdbarch);
   if (n_args < 2)
     error (_("C++ exception catchpoint has too few arguments"));
 
   if (arg0 != NULL)
-    *arg0 = pc_probe_fns->sym_evaluate_probe_argument (pc_probe, 0);
-  *arg1 = pc_probe_fns->sym_evaluate_probe_argument (pc_probe, 1);
+    *arg0 = pc_probe_fns->sym_evaluate_probe_argument (pc_probe, 0, gdbarch);
+  *arg1 = pc_probe_fns->sym_evaluate_probe_argument (pc_probe, 1, gdbarch);
 
   if ((arg0 != NULL && *arg0 == NULL) || *arg1 == NULL)
     error (_("error computing probe argument at c++ exception catchpoint"));
diff --git a/gdb/elfread.c b/gdb/elfread.c
index 42ab18f..b72cd96 100644
--- a/gdb/elfread.c
+++ b/gdb/elfread.c
@@ -1509,27 +1509,30 @@ elf_get_probes (struct objfile *objfile)
    symfile.h.  */
 
 static unsigned
-elf_get_probe_argument_count (struct probe *probe)
+elf_get_probe_argument_count (struct probe *probe,
+			      struct gdbarch *gdbarch)
 {
-  return probe->pops->get_probe_argument_count (probe);
+  return probe->pops->get_probe_argument_count (probe, gdbarch);
 }
 
 /* Implementation of `sym_can_evaluate_probe_arguments', as documented in
    symfile.h.  */
 
 static int
-elf_can_evaluate_probe_arguments (struct probe *probe)
+elf_can_evaluate_probe_arguments (struct probe *probe,
+				  struct gdbarch *gdbarch)
 {
-  return probe->pops->can_evaluate_probe_arguments (probe);
+  return probe->pops->can_evaluate_probe_arguments (probe, gdbarch);
 }
 
 /* Implementation of `sym_evaluate_probe_argument', as documented in
    symfile.h.  */
 
 static struct value *
-elf_evaluate_probe_argument (struct probe *probe, unsigned n)
+elf_evaluate_probe_argument (struct probe *probe, unsigned n,
+			     struct gdbarch *gdbarch)
 {
-  return probe->pops->evaluate_probe_argument (probe, n);
+  return probe->pops->evaluate_probe_argument (probe, n, gdbarch);
 }
 
 /* Implementation of `sym_compile_to_ax', as documented in symfile.h.  */
diff --git a/gdb/probe.c b/gdb/probe.c
index 4046701..37314dd 100644
--- a/gdb/probe.c
+++ b/gdb/probe.c
@@ -617,6 +617,8 @@ unsigned
 get_probe_argument_count (struct probe *probe)
 {
   const struct sym_probe_fns *probe_fns;
+  struct frame_info *frame = get_selected_frame (_("No frame selected"));
+  struct gdbarch *gdbarch = get_frame_arch (frame);
 
   gdb_assert (probe->objfile != NULL);
   gdb_assert (probe->objfile->sf != NULL);
@@ -625,7 +627,7 @@ get_probe_argument_count (struct probe *probe)
 
   gdb_assert (probe_fns != NULL);
 
-  return probe_fns->sym_get_probe_argument_count (probe);
+  return probe_fns->sym_get_probe_argument_count (probe, gdbarch);
 }
 
 /* See comments in probe.h.  */
@@ -634,6 +636,8 @@ int
 can_evaluate_probe_arguments (struct probe *probe)
 {
   const struct sym_probe_fns *probe_fns;
+  struct frame_info *frame = get_selected_frame (_("No frame selected"));
+  struct gdbarch *gdbarch = get_frame_arch (frame);
 
   gdb_assert (probe->objfile != NULL);
   gdb_assert (probe->objfile->sf != NULL);
@@ -642,7 +646,7 @@ can_evaluate_probe_arguments (struct probe *probe)
 
   gdb_assert (probe_fns != NULL);
 
-  return probe_fns->can_evaluate_probe_arguments (probe);
+  return probe_fns->can_evaluate_probe_arguments (probe, gdbarch);
 }
 
 /* See comments in probe.h.  */
@@ -651,6 +655,8 @@ struct value *
 evaluate_probe_argument (struct probe *probe, unsigned n)
 {
   const struct sym_probe_fns *probe_fns;
+  struct frame_info *frame = get_selected_frame (_("No frame selected"));
+  struct gdbarch *gdbarch = get_frame_arch (frame);
 
   gdb_assert (probe->objfile != NULL);
   gdb_assert (probe->objfile->sf != NULL);
@@ -659,7 +665,7 @@ evaluate_probe_argument (struct probe *probe, unsigned n)
 
   gdb_assert (probe_fns != NULL);
 
-  return probe_fns->sym_evaluate_probe_argument (probe, n);
+  return probe_fns->sym_evaluate_probe_argument (probe, n, gdbarch);
 }
 
 /* See comments in probe.h.  */
diff --git a/gdb/probe.h b/gdb/probe.h
index dd5387b..6a08f3d 100644
--- a/gdb/probe.h
+++ b/gdb/probe.h
@@ -71,19 +71,22 @@ struct probe_ops
 
     /* Return the number of arguments of PROBE.  */
 
-    unsigned (*get_probe_argument_count) (struct probe *probe);
+    unsigned (*get_probe_argument_count) (struct probe *probe,
+					  struct gdbarch *gdbarch);
 
     /* Return 1 if the probe interface can evaluate the arguments of probe
        PROBE, zero otherwise.  See the comments on
        sym_probe_fns:can_evaluate_probe_arguments for more details.  */
 
-    int (*can_evaluate_probe_arguments) (struct probe *probe);
+    int (*can_evaluate_probe_arguments) (struct probe *probe,
+					 struct gdbarch *gdbarch);
 
     /* Evaluate the Nth argument from the PROBE, returning a value
        corresponding to it.  The argument number is represented N.  */
 
     struct value *(*evaluate_probe_argument) (struct probe *probe,
-					      unsigned n);
+					      unsigned n,
+					      struct gdbarch *gdbarch);
 
     /* Compile the Nth argument of the PROBE to an agent expression.
        The argument number is represented by N.  */
diff --git a/gdb/stap-probe.c b/gdb/stap-probe.c
index a734793..e8b5805 100644
--- a/gdb/stap-probe.c
+++ b/gdb/stap-probe.c
@@ -38,6 +38,7 @@
 #include "parser-defs.h"
 #include "language.h"
 #include "elf-bfd.h"
+#include "regcache.h"
 
 #include <ctype.h>
 
@@ -914,10 +915,9 @@ stap_parse_argument (const char **arg, struct type *atype,
    this information.  */
 
 static void
-stap_parse_probe_arguments (struct stap_probe *probe)
+stap_parse_probe_arguments (struct stap_probe *probe, struct gdbarch *gdbarch)
 {
   const char *cur;
-  struct gdbarch *gdbarch = get_objfile_arch (probe->p.objfile);
 
   gdb_assert (!probe->args_parsed);
   cur = probe->args_u.text;
@@ -1002,7 +1002,8 @@ stap_parse_probe_arguments (struct stap_probe *probe)
    argument string.  */
 
 static unsigned
-stap_get_probe_argument_count (struct probe *probe_generic)
+stap_get_probe_argument_count (struct probe *probe_generic,
+			       struct gdbarch *gdbarch)
 {
   struct stap_probe *probe = (struct stap_probe *) probe_generic;
 
@@ -1010,8 +1011,9 @@ stap_get_probe_argument_count (struct probe *probe_generic)
 
   if (!probe->args_parsed)
     {
-      if (probe_generic->pops->can_evaluate_probe_arguments (probe_generic))
-	stap_parse_probe_arguments (probe);
+      if (probe_generic->pops->can_evaluate_probe_arguments (probe_generic,
+							     gdbarch))
+	stap_parse_probe_arguments (probe, gdbarch);
       else
 	{
 	  static int have_warned_stap_incomplete = 0;
@@ -1072,10 +1074,10 @@ stap_is_operator (const char *op)
 }
 
 static struct stap_probe_arg *
-stap_get_arg (struct stap_probe *probe, unsigned n)
+stap_get_arg (struct stap_probe *probe, unsigned n, struct gdbarch *gdbarch)
 {
   if (!probe->args_parsed)
-    stap_parse_probe_arguments (probe);
+    stap_parse_probe_arguments (probe, gdbarch);
 
   return VEC_index (stap_probe_arg_s, probe->args_u.vec, n);
 }
@@ -1083,10 +1085,10 @@ stap_get_arg (struct stap_probe *probe, unsigned n)
 /* Implement the `can_evaluate_probe_arguments' method of probe_ops.  */
 
 static int
-stap_can_evaluate_probe_arguments (struct probe *probe_generic)
+stap_can_evaluate_probe_arguments (struct probe *probe_generic,
+				   struct gdbarch *gdbarch)
 {
   struct stap_probe *stap_probe = (struct stap_probe *) probe_generic;
-  struct gdbarch *gdbarch = get_objfile_arch (stap_probe->p.objfile);
 
   /* For SystemTap probes, we have to guarantee that the method
      stap_is_single_operand is defined on gdbarch.  If it is not, then it
@@ -1098,7 +1100,8 @@ stap_can_evaluate_probe_arguments (struct probe *probe_generic)
    corresponding to it.  Assertion is thrown if N does not exist.  */
 
 static struct value *
-stap_evaluate_probe_argument (struct probe *probe_generic, unsigned n)
+stap_evaluate_probe_argument (struct probe *probe_generic, unsigned n,
+			      struct gdbarch *gdbarch)
 {
   struct stap_probe *stap_probe = (struct stap_probe *) probe_generic;
   struct stap_probe_arg *arg;
@@ -1106,7 +1109,7 @@ stap_evaluate_probe_argument (struct probe *probe_generic, unsigned n)
 
   gdb_assert (probe_generic->pops == &stap_probe_ops);
 
-  arg = stap_get_arg (stap_probe, n);
+  arg = stap_get_arg (stap_probe, n, gdbarch);
   return evaluate_subexp_standard (arg->atype, arg->aexpr, &pos, EVAL_NORMAL);
 }
 
@@ -1123,7 +1126,7 @@ stap_compile_to_ax (struct probe *probe_generic, struct agent_expr *expr,
 
   gdb_assert (probe_generic->pops == &stap_probe_ops);
 
-  arg = stap_get_arg (stap_probe, n);
+  arg = stap_get_arg (stap_probe, n, expr->gdbarch);
 
   pc = arg->aexpr->elts;
   gen_expr (arg->aexpr, &pc, expr, value);
@@ -1165,6 +1168,7 @@ compute_probe_arg (struct gdbarch *arch, struct internalvar *ivar,
 {
   struct frame_info *frame = get_selected_frame (_("No frame selected"));
   CORE_ADDR pc = get_frame_pc (frame);
+  struct gdbarch *gdbarch = get_frame_arch (frame);
   int sel = (int) (uintptr_t) data;
   struct probe *pc_probe;
   const struct sym_probe_fns *pc_probe_fns;
@@ -1183,7 +1187,7 @@ compute_probe_arg (struct gdbarch *arch, struct internalvar *ivar,
 
   pc_probe_fns = pc_probe->objfile->sf->sym_probe_fns;
 
-  n_args = pc_probe_fns->sym_get_probe_argument_count (pc_probe);
+  n_args = pc_probe_fns->sym_get_probe_argument_count (pc_probe, gdbarch);
   if (sel == -1)
     return value_from_longest (builtin_type (arch)->builtin_int, n_args);
 
@@ -1191,7 +1195,7 @@ compute_probe_arg (struct gdbarch *arch, struct internalvar *ivar,
     error (_("Invalid probe argument %d -- probe has %u arguments available"),
 	   sel, n_args);
 
-  return pc_probe_fns->sym_evaluate_probe_argument (pc_probe, sel);
+  return pc_probe_fns->sym_evaluate_probe_argument (pc_probe, sel, gdbarch);
 }
 
 /* This is called to compile one of the $_probe_arg* convenience
@@ -1220,7 +1224,8 @@ compile_probe_arg (struct internalvar *ivar, struct agent_expr *expr,
 
   pc_probe_fns = pc_probe->objfile->sf->sym_probe_fns;
 
-  n_args = pc_probe_fns->sym_get_probe_argument_count (pc_probe);
+  n_args = pc_probe_fns->sym_get_probe_argument_count (pc_probe,
+						       expr->gdbarch);
 
   if (sel == -1)
     {
@@ -1333,11 +1338,11 @@ static const struct internalvar_funcs probe_funcs =
 
 static void
 handle_stap_probe (struct objfile *objfile, struct sdt_note *el,
-		   VEC (probe_p) **probesp, CORE_ADDR base)
+		   VEC (probe_p) **probesp, CORE_ADDR base,
+		   struct gdbarch *gdbarch)
 {
   bfd *abfd = objfile->obfd;
   int size = bfd_get_arch_size (abfd) / 8;
-  struct gdbarch *gdbarch = get_objfile_arch (objfile);
   struct type *ptr_type = builtin_type (gdbarch)->builtin_data_ptr;
   CORE_ADDR base_ref;
   const char *probe_args = NULL;
@@ -1461,6 +1466,8 @@ stap_get_probes (VEC (probe_p) **probesp, struct objfile *objfile)
   bfd_vma base;
   struct sdt_note *iter;
   unsigned save_probesp_len = VEC_length (probe_p, *probesp);
+  struct regcache *regcache = get_current_regcache ();
+  struct gdbarch *gdbarch = get_regcache_arch (regcache);
 
   if (objfile->separate_debug_objfile_backlink != NULL)
     {
@@ -1486,7 +1493,7 @@ stap_get_probes (VEC (probe_p) **probesp, struct objfile *objfile)
     {
       /* We first have to handle all the information about the
 	 probe which is present in the section.  */
-      handle_stap_probe (objfile, iter, probesp, base);
+      handle_stap_probe (objfile, iter, probesp, base, gdbarch);
     }
 
   if (save_probesp_len == VEC_length (probe_p, *probesp))
@@ -1535,13 +1542,12 @@ stap_gen_info_probes_table_values (struct probe *probe_generic,
 				   VEC (const_char_ptr) **ret)
 {
   struct stap_probe *probe = (struct stap_probe *) probe_generic;
-  struct gdbarch *gdbarch;
+  struct frame_info *frame = get_selected_frame (_("No frame selected"));
+  struct gdbarch *gdbarch = get_frame_arch (frame);
   const char *val = NULL;
 
   gdb_assert (probe_generic->pops == &stap_probe_ops);
 
-  gdbarch = get_objfile_arch (probe->p.objfile);
-
   if (probe->sem_addr)
     val = print_core_address (gdbarch, probe->sem_addr);
 
diff --git a/gdb/symfile-debug.c b/gdb/symfile-debug.c
index b6e84d1..eb6f000 100644
--- a/gdb/symfile-debug.c
+++ b/gdb/symfile-debug.c
@@ -393,7 +393,8 @@ debug_sym_get_probes (struct objfile *objfile)
 }
 
 static unsigned
-debug_sym_get_probe_argument_count (struct probe *probe)
+debug_sym_get_probe_argument_count (struct probe *probe,
+				    struct gdbarch *gdbarch)
 {
   struct objfile *objfile = probe->objfile;
   const struct debug_sym_fns_data *debug_data =
@@ -401,7 +402,7 @@ debug_sym_get_probe_argument_count (struct probe *probe)
   unsigned retval;
 
   retval = debug_data->real_sf->sym_probe_fns->sym_get_probe_argument_count
-    (probe);
+    (probe, gdbarch);
 
   fprintf_filtered (gdb_stdlog,
 		    "probes->sym_get_probe_argument_count (%s) = %u\n",
@@ -411,7 +412,8 @@ debug_sym_get_probe_argument_count (struct probe *probe)
 }
 
 static int
-debug_can_evaluate_probe_arguments (struct probe *probe)
+debug_can_evaluate_probe_arguments (struct probe *probe,
+				    struct gdbarch *gdbarch)
 {
   struct objfile *objfile = probe->objfile;
   const struct debug_sym_fns_data *debug_data =
@@ -419,7 +421,7 @@ debug_can_evaluate_probe_arguments (struct probe *probe)
   int retval;
 
   retval = debug_data->real_sf->sym_probe_fns->can_evaluate_probe_arguments
-    (probe);
+    (probe, gdbarch);
 
   fprintf_filtered (gdb_stdlog,
 		    "probes->can_evaluate_probe_arguments (%s) = %d\n",
@@ -429,7 +431,8 @@ debug_can_evaluate_probe_arguments (struct probe *probe)
 }
 
 static struct value *
-debug_sym_evaluate_probe_argument (struct probe *probe, unsigned n)
+debug_sym_evaluate_probe_argument (struct probe *probe, unsigned n,
+				   struct gdbarch *gdbarch)
 {
   struct objfile *objfile = probe->objfile;
   const struct debug_sym_fns_data *debug_data =
@@ -441,7 +444,7 @@ debug_sym_evaluate_probe_argument (struct probe *probe, unsigned n)
 		    host_address_to_string (probe), n);
 
   retval = debug_data->real_sf->sym_probe_fns->sym_evaluate_probe_argument
-    (probe, n);
+    (probe, n, gdbarch);
 
   fprintf_filtered (gdb_stdlog,
 		    "probes->sym_evaluate_probe_argument (...) = %s\n",
diff --git a/gdb/symfile.h b/gdb/symfile.h
index 8e5909b..4c4a0dd 100644
--- a/gdb/symfile.h
+++ b/gdb/symfile.h
@@ -309,7 +309,8 @@ struct sym_probe_fns
      have come from a call to this objfile's sym_get_probes method.
      If you provide an implementation of sym_get_probes, you must
      implement this method as well.  */
-  unsigned (*sym_get_probe_argument_count) (struct probe *probe);
+  unsigned (*sym_get_probe_argument_count) (struct probe *probe,
+					    struct gdbarch *gdbarch);
 
   /* Return 1 if the probe interface can evaluate the arguments of probe
      PROBE, zero otherwise.  This function can be probe-specific, informing
@@ -317,7 +318,8 @@ struct sym_probe_fns
      informing whether the probe interface is able to evaluate any kind of
      argument.  If you provide an implementation of sym_get_probes, you must
      implement this method as well.  */
-  int (*can_evaluate_probe_arguments) (struct probe *probe);
+  int (*can_evaluate_probe_arguments) (struct probe *probe,
+				       struct gdbarch *gdbarch);
 
   /* Evaluate the Nth argument available to PROBE.  PROBE will have
      come from a call to this objfile's sym_get_probes method.  N will
@@ -327,7 +329,8 @@ struct sym_probe_fns
      implementation of sym_get_probes, you must implement this method
      as well.  */
   struct value *(*sym_evaluate_probe_argument) (struct probe *probe,
-						unsigned n);
+						unsigned n,
+						struct gdbarch *gdbarch);
 
   /* Compile the Nth probe argument to an agent expression.  PROBE
      will have come from a call to this objfile's sym_get_probes


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